1. Technical Field
The present invention relates to centrifugal fans suited to cooling miniature devices that give off heat, and to heatsinks that with the centrifugal fan being mounted on them demonstrate excellent performance. In particular the present invention relates to centrifugal fans suited to being built into portable electronic devices, and to heatsinks furnished with the centrifugal fans.
2. Background Art
With upgrading in the performance of electronic devices such as personal computers proceeding rapidly in recent years, there has been a trend toward an increase in the amount of heat issuing from devices such as CPUs, peripheral integrated circuits, hard disks, and power-supply circuits. In addition, as devices are being slimmed down and miniaturized further, the necessity for cooling mechanisms demonstrating sufficient cooling power within narrow confines has arisen. Such trends have been especially pronounced in so-called notebook personal computers. With desktop personal computers also there have been similar demands, owing to the tendency for consumers to prefer more scaled-down products.
What is more, with the further scaling down of, and higher-density mounting of electronic components in, portable telephones, PDAs (personal data assistants), and like devices leading to dramatically upgraded performance, temperature elevation in the interior of the devices is becoming impossible to ignore. New cooling mechanisms are also becoming necessary in such applications as these.
Traditionally for cooling personal computers, axial fans have chiefly been utilized. This is because securing the airflow rate necessary for cooling is comparatively easy. On the other hand, in situations in which, owing to the low static pressure of axial fans on the whole, higher static pressure is required, methods such as utilizing a centrifugal fan, or arranging axial fans in series have been employed.
Fans that provide high static pressure are required for cooling slim-profile notebook computers, which are a target of the present invention, owing to the limited clearances through which air can circulate inside the computer case. At the same time, however, with the fans having to be scaled-down and slim-profile, the heatsinks employed in combination with the fans too must of necessity be slim-profile.
A heatsink and axial fan, devised in order to cool integrated circuits installed in a notebook computer or the like, are set forth in Japanese Pat. Pub. No. 3,392,527. Although in this instance the axial fan is provided with a cylindrical projection to heighten its static pressure, because the fan in and of itself is axial-flow, its static pressure is relatively low. Moreover, the fan's significant windage loss is prohibitive of securing sufficient airflow rate.
An example of a cooling-mechanism configuration in which a centrifugal-fan is installed inside a notebook computer is disclosed in Japanese Unexamined Pat. App. Pub. No. 2003-023128. Although the centrifugal fan, owing to its large static pressure, has sufficient cooling power, the fact that it takes up a large amount of space within the case is a drawback. And while making the case a bit bigger would enable a mechanism of this sort to be installed in notebook computers, applying this technology to the even smaller-scale PDAs, mobile telephones, and similar devices would pose difficulties.